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Indicator Assessment
Trends in the duration of wet (left) and dry (right) spells
Note: Black dots show trends that are statistically significant (at the 5% level). Boxes with an outline contain at least three stations. Area averaged annual time series of percentage changes and trend lines are shown below each map for one area in northern Europe (blue line, 5.6 to 16.9 °E and 56.2 to 66.2 °N) and one in south-western Europe (red line, 9.4 °W to 1.9 °E and 36.2 to 43.7 °N).
Projected changes in heavy precipitation in winter and summer
Past trends
This indicator assesses two aspects of extreme precipitation: heavy precipitation, which may lead to flooding, and long dry spells, which can cause droughts. Heavy precipitation can be further distinguished into multi-day heavy precipitation, which often covers large regions and can lead to large-scale river floods, and short-term heavy precipitation, which is often localized and can lead to flash floods. The observed changes in heavy precipitation in Europe are region and season specific (Zolina 2012). The dominating tendency for many regions, using several indices, is that heavy precipitation has been increasing.
Observation records show significant increases in the duration of wet spells since 1960 in north-eastern Europe, whereas significant decreases (by up to 4 days per decade) have been observed in south-western Europe (Besselaar et al. 2013) (Fig. 1 left). Seasonal changes have also been noted with an increase in the frequency and intensity of winter precipitation in central and eastern Europe (Hov et al. 2013, Zolina 2012).
Data availability is insufficient for assessing trends in short-term heavy precipitation across Europe. Available studies found increasing trends in extreme daily winter precipitation in many regions, including central and western Europe, whereas in some regions decreasing trends were found (Hov et al. 2013).
No significant changes in the annually averaged duration of dry spells since 1960 have been observed across Europe (Fig. 1 right). However, there is high confidence of increasing summer dryness since the 1950s in central and southern Europe, with the largest increases in western and central Mediterranean (Sousa et al. 2011, Hov et al. 2013).
Projections
Global warming is projected to lead to higher intensity of precipitation and longer dry periods in Europe (Hov et al. 2013, IPCC 2012). Model-based projections for the period 2071-2100 show an increase (compared to the period 1971-2000) in heavy precipitation in most parts of Europe, with the exception of the Iberian Peninsula and Mediterranean regions in summer (Fig. 2). Heavy precipitation events are likely to increase in most parts of Europe in winter by up to 35 % (Jacob et al. 2013, Rajczak et al. 2013, IPCC 2012). During summers decreases (between 15 and 25 %) are projected in the Mediterranean region.
Projected changes in length of dry spells show significant increases by up to 24 days in southern Europe and decreases (between 1 and 2 days) in northern Europe (Jacob et al. 2013) (Fig. 3). Other drought indices show similar geographical and seasonal patterns (IPCC 2012, 2014).
In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.
The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.
No targets have been specified.
The number of consecutive wet days is defined as the number of days in a row during which every day is a wet day (daily precipitation amounts are more than 1 mm in every day during the period). Respectively, consecutive dry days show less than 1 mm per day. Ensemble of RCMs driven by different GCMs all using RCP8.5 scenario has been used to calculate changes in heavy precipitation and dry spells. Heavy precipitation is defined as the intensity of the heavy precipitation events defined as the 95th percentile of daily precipitation (only days with precipitation higher than 1 mm/day are considered). Dry spells are defined as periods of at least 5 consecutive days with daily precipitation below 1 mm.
Not applicable
No methodology references available.
Not applicable
The risks posed by precipitation-related hazards, such as flooding events (including flash floods) and landslides, are also influenced by non-climatic factors, such as population density, floodplain development and land-use change. Hence, estimates of future changes in such risks need to consider changes in both climatic and non-climatic factors. Estimates of trends in heavy or extreme precipitation are more uncertain than trends in mean precipitation because, by their very nature, extreme precipitation events have a low frequency of occurrence. This leads to greater uncertainties when assessing the statistical significance of observed changes.
Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/
No uncertainty has been specified
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/precipitation-extremes-in-europe-2/assessment or scan the QR code.
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